In the field of transport vehicles it is known practice to fix seats intended for the passengers or for crew members to the structure of the vehicle.
In the known way, the seats are often fixed to the floor of the vehicle either at fixed predetermined locations or on rails secured to the floor that allow each seat to be positioned at various locations without having to rework the floor structure and the fixing points.
The latter solution is widely used in the case of aircraft where it allows very different configurations to be set out according to the type of comfort desired by the aircraft operator.
The latter solution can also, as illustrated in FIG. 1, be used in the case of a seat 10 with what is referred to as a monobeam structure, in which a seat cushion and backrest assembly 11 is secured to a substantially vertical beam 12, inclined to a greater or lesser extent, generally towards the rear of the seat, with respect to the vertical.
The beam 12 is then secured to a support structure 13 comprising fixing points which are set out for being fixed to the rails 14 of the floor 15.
In these solutions it is necessary to have mechanical clearances which are needed for absorbing defective positioning of the fixing points caused by manufacturing tolerances or caused by deformations in the structures, whether these fixing points are directly on the structure or whether they are on rails. These required clearances therefore lead to feelings of instability for the occupants of the seats and to noises when the seat is in a vibrational environment, as, in vehicles, it often is.
Furthermore, the seat is generally required to have comfort settings which, when the seat is fixed to the floor, allow the seat cushion and the backrest to be moved, usually longitudinally, vertically and in terms of inclination. These adjustments when desired on the seat entail additional mechanisms independent of the means of fixing to the floor and which, leaving aside their complexities and cost, increase the mass of the seat, notably in the upper parts of the seat, the consequences of this being that the structure has to be reinforced in order to meet crash testing requirements, something which particularly in aeronautical applications proves to be penalizing. The clearances necessary for fixing the seat are also a source of defective operation in the sliding parts of the seats.